/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.runtime;

import java.io.CharArrayReader;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;

import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyContent;

import org.apache.jasper.Constants;

/**
 * Write text to a character-output stream, buffering characters so as to
 * provide for the efficient writing of single characters, arrays, and strings.
 * 
 * Provide support for discarding for the output that has been buffered.
 * 
 * @author Rajiv Mordani
 * @author Jan Luehe
 */
public class BodyContentImpl extends BodyContent {

	private static final String LINE_SEPARATOR = System
			.getProperty("line.separator");
	private static final boolean LIMIT_BUFFER = Boolean.valueOf(
			System.getProperty(
					"org.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER",
					"false")).booleanValue();

	private char[] cb;
	private int nextChar;
	private boolean closed;

	// Enclosed writer to which any output is written
	private Writer writer;

	// See comment in setWriter()
	private int bufferSizeSave;

	/**
	 * Constructor.
	 */
	public BodyContentImpl(JspWriter enclosingWriter) {
		super(enclosingWriter);
		bufferSize = Constants.DEFAULT_TAG_BUFFER_SIZE;
		cb = new char[bufferSize];
		nextChar = 0;
		closed = false;
	}

	/**
	 * Write a single character.
	 */
	public void write(int c) throws IOException {
		if (writer != null) {
			writer.write(c);
		} else {
			ensureOpen();
			if (nextChar >= bufferSize) {
				reAllocBuff(1);
			}
			cb[nextChar++] = (char) c;
		}
	}

	/**
	 * Write a portion of an array of characters.
	 * 
	 * <p>
	 * Ordinarily this method stores characters from the given array into this
	 * stream's buffer, flushing the buffer to the underlying stream as needed.
	 * If the requested length is at least as large as the buffer, however, then
	 * this method will flush the buffer and write the characters directly to
	 * the underlying stream. Thus redundant
	 * <code>DiscardableBufferedWriter</code>s will not copy data
	 * unnecessarily.
	 * 
	 * @param cbuf
	 *            A character array
	 * @param off
	 *            Offset from which to start reading characters
	 * @param len
	 *            Number of characters to write
	 */
	public void write(char[] cbuf, int off, int len) throws IOException {
		if (writer != null) {
			writer.write(cbuf, off, len);
		} else {
			ensureOpen();

			if ((off < 0) || (off > cbuf.length) || (len < 0)
					|| ((off + len) > cbuf.length) || ((off + len) < 0)) {
				throw new IndexOutOfBoundsException();
			} else if (len == 0) {
				return;
			}

			if (len >= bufferSize - nextChar)
				reAllocBuff(len);

			System.arraycopy(cbuf, off, cb, nextChar, len);
			nextChar += len;
		}
	}

	/**
	 * Write an array of characters. This method cannot be inherited from the
	 * Writer class because it must suppress I/O exceptions.
	 */
	public void write(char[] buf) throws IOException {
		if (writer != null) {
			writer.write(buf);
		} else {
			write(buf, 0, buf.length);
		}
	}

	/**
	 * Write a portion of a String.
	 * 
	 * @param s
	 *            String to be written
	 * @param off
	 *            Offset from which to start reading characters
	 * @param len
	 *            Number of characters to be written
	 */
	public void write(String s, int off, int len) throws IOException {
		if (writer != null) {
			writer.write(s, off, len);
		} else {
			ensureOpen();
			if (len >= bufferSize - nextChar)
				reAllocBuff(len);

			s.getChars(off, off + len, cb, nextChar);
			nextChar += len;
		}
	}

	/**
	 * Write a string. This method cannot be inherited from the Writer class
	 * because it must suppress I/O exceptions.
	 */
	public void write(String s) throws IOException {
		if (writer != null) {
			writer.write(s);
		} else {
			write(s, 0, s.length());
		}
	}

	/**
	 * Write a line separator. The line separator string is defined by the
	 * system property <tt>line.separator</tt>, and is not necessarily a
	 * single newline ('\n') character.
	 * 
	 * @throws IOException
	 *             If an I/O error occurs
	 */
	public void newLine() throws IOException {
		if (writer != null) {
			writer.write(LINE_SEPARATOR);
		} else {
			write(LINE_SEPARATOR);
		}
	}

	/**
	 * Print a boolean value. The string produced by <code>{@link
	 * java.lang.String#valueOf(boolean)}</code>
	 * is translated into bytes according to the platform's default character
	 * encoding, and these bytes are written in exactly the manner of the
	 * <code>{@link
	 * #write(int)}</code> method.
	 * 
	 * @param b
	 *            The <code>boolean</code> to be printed
	 * @throws IOException
	 */
	public void print(boolean b) throws IOException {
		if (writer != null) {
			writer.write(b ? "true" : "false");
		} else {
			write(b ? "true" : "false");
		}
	}

	/**
	 * Print a character. The character is translated into one or more bytes
	 * according to the platform's default character encoding, and these bytes
	 * are written in exactly the manner of the <code>{@link
	 * #write(int)}</code>
	 * method.
	 * 
	 * @param c
	 *            The <code>char</code> to be printed
	 * @throws IOException
	 */
	public void print(char c) throws IOException {
		if (writer != null) {
			writer.write(String.valueOf(c));
		} else {
			write(String.valueOf(c));
		}
	}

	/**
	 * Print an integer. The string produced by <code>{@link
	 * java.lang.String#valueOf(int)}</code>
	 * is translated into bytes according to the platform's default character
	 * encoding, and these bytes are written in exactly the manner of the
	 * <code>{@link #write(int)}</code> method.
	 * 
	 * @param i
	 *            The <code>int</code> to be printed
	 * @throws IOException
	 */
	public void print(int i) throws IOException {
		if (writer != null) {
			writer.write(String.valueOf(i));
		} else {
			write(String.valueOf(i));
		}
	}

	/**
	 * Print a long integer. The string produced by <code>{@link
	 * java.lang.String#valueOf(long)}</code>
	 * is translated into bytes according to the platform's default character
	 * encoding, and these bytes are written in exactly the manner of the
	 * <code>{@link #write(int)}</code> method.
	 * 
	 * @param l
	 *            The <code>long</code> to be printed
	 * @throws IOException
	 */
	public void print(long l) throws IOException {
		if (writer != null) {
			writer.write(String.valueOf(l));
		} else {
			write(String.valueOf(l));
		}
	}

	/**
	 * Print a floating-point number. The string produced by <code>{@link
	 * java.lang.String#valueOf(float)}</code>
	 * is translated into bytes according to the platform's default character
	 * encoding, and these bytes are written in exactly the manner of the
	 * <code>{@link #write(int)}</code> method.
	 * 
	 * @param f
	 *            The <code>float</code> to be printed
	 * @throws IOException
	 */
	public void print(float f) throws IOException {
		if (writer != null) {
			writer.write(String.valueOf(f));
		} else {
			write(String.valueOf(f));
		}
	}

	/**
	 * Print a double-precision floating-point number. The string produced by
	 * <code>{@link java.lang.String#valueOf(double)}</code> is translated
	 * into bytes according to the platform's default character encoding, and
	 * these bytes are written in exactly the manner of the <code>{@link
	 * #write(int)}</code>
	 * method.
	 * 
	 * @param d
	 *            The <code>double</code> to be printed
	 * @throws IOException
	 */
	public void print(double d) throws IOException {
		if (writer != null) {
			writer.write(String.valueOf(d));
		} else {
			write(String.valueOf(d));
		}
	}

	/**
	 * Print an array of characters. The characters are converted into bytes
	 * according to the platform's default character encoding, and these bytes
	 * are written in exactly the manner of the <code>{@link #write(int)}</code>
	 * method.
	 * 
	 * @param s
	 *            The array of chars to be printed
	 * 
	 * @throws NullPointerException
	 *             If <code>s</code> is <code>null</code>
	 * @throws IOException
	 */
	public void print(char[] s) throws IOException {
		if (writer != null) {
			writer.write(s);
		} else {
			write(s);
		}
	}

	/**
	 * Print a string. If the argument is <code>null</code> then the string
	 * <code>"null"</code> is printed. Otherwise, the string's characters are
	 * converted into bytes according to the platform's default character
	 * encoding, and these bytes are written in exactly the manner of the
	 * <code>{@link #write(int)}</code> method.
	 * 
	 * @param s
	 *            The <code>String</code> to be printed
	 * @throws IOException
	 */
	public void print(String s) throws IOException {
		if (s == null)
			s = "null";
		if (writer != null) {
			writer.write(s);
		} else {
			write(s);
		}
	}

	/**
	 * Print an object. The string produced by the <code>{@link
	 * java.lang.String#valueOf(Object)}</code>
	 * method is translated into bytes according to the platform's default
	 * character encoding, and these bytes are written in exactly the manner of
	 * the <code>{@link #write(int)}</code> method.
	 * 
	 * @param obj
	 *            The <code>Object</code> to be printed
	 * @throws IOException
	 */
	public void print(Object obj) throws IOException {
		if (writer != null) {
			writer.write(String.valueOf(obj));
		} else {
			write(String.valueOf(obj));
		}
	}

	/**
	 * Terminate the current line by writing the line separator string. The line
	 * separator string is defined by the system property
	 * <code>line.separator</code>, and is not necessarily a single newline
	 * character (<code>'\n'</code>).
	 * 
	 * @throws IOException
	 */
	public void println() throws IOException {
		newLine();
	}

	/**
	 * Print a boolean value and then terminate the line. This method behaves as
	 * though it invokes <code>{@link #print(boolean)}</code> and then
	 * <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(boolean x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print a character and then terminate the line. This method behaves as
	 * though it invokes <code>{@link #print(char)}</code> and then
	 * <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(char x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print an integer and then terminate the line. This method behaves as
	 * though it invokes <code>{@link #print(int)}</code> and then
	 * <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(int x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print a long integer and then terminate the line. This method behaves as
	 * though it invokes <code>{@link #print(long)}</code> and then
	 * <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(long x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print a floating-point number and then terminate the line. This method
	 * behaves as though it invokes <code>{@link #print(float)}</code> and
	 * then <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(float x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print a double-precision floating-point number and then terminate the
	 * line. This method behaves as though it invokes <code>{@link
	 * #print(double)}</code>
	 * and then <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(double x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print an array of characters and then terminate the line. This method
	 * behaves as though it invokes <code>{@link #print(char[])}</code> and
	 * then <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(char x[]) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print a String and then terminate the line. This method behaves as though
	 * it invokes <code>{@link #print(String)}</code> and then
	 * <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(String x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Print an Object and then terminate the line. This method behaves as
	 * though it invokes <code>{@link #print(Object)}</code> and then
	 * <code>{@link #println()}</code>.
	 * 
	 * @throws IOException
	 */
	public void println(Object x) throws IOException {
		print(x);
		println();
	}

	/**
	 * Clear the contents of the buffer. If the buffer has been already been
	 * flushed then the clear operation shall throw an IOException to signal the
	 * fact that some data has already been irrevocably written to the client
	 * response stream.
	 * 
	 * @throws IOException
	 *             If an I/O error occurs
	 */
	public void clear() throws IOException {
		if (writer != null) {
			throw new IOException();
		} else {
			nextChar = 0;
			if (LIMIT_BUFFER && (cb.length > Constants.DEFAULT_TAG_BUFFER_SIZE)) {
				bufferSize = Constants.DEFAULT_TAG_BUFFER_SIZE;
				cb = new char[bufferSize];
			}
		}
	}

	/**
	 * Clears the current contents of the buffer. Unlike clear(), this mehtod
	 * will not throw an IOException if the buffer has already been flushed. It
	 * merely clears the current content of the buffer and returns.
	 * 
	 * @throws IOException
	 *             If an I/O error occurs
	 */
	public void clearBuffer() throws IOException {
		if (writer == null) {
			this.clear();
		}
	}

	/**
	 * Close the stream, flushing it first. Once a stream has been closed,
	 * further write() or flush() invocations will cause an IOException to be
	 * thrown. Closing a previously-closed stream, however, has no effect.
	 * 
	 * @throws IOException
	 *             If an I/O error occurs
	 */
	public void close() throws IOException {
		if (writer != null) {
			writer.close();
		} else {
			closed = true;
		}
	}

	/**
	 * @return the number of bytes unused in the buffer
	 */
	public int getRemaining() {
		return (writer == null) ? bufferSize - nextChar : 0;
	}

	/**
	 * Return the value of this BodyJspWriter as a Reader. Note: this is after
	 * evaluation!! There are no scriptlets, etc in this stream.
	 * 
	 * @return the value of this BodyJspWriter as a Reader
	 */
	public Reader getReader() {
		return (writer == null) ? new CharArrayReader(cb, 0, nextChar) : null;
	}

	/**
	 * Return the value of the BodyJspWriter as a String. Note: this is after
	 * evaluation!! There are no scriptlets, etc in this stream.
	 * 
	 * @return the value of the BodyJspWriter as a String
	 */
	public String getString() {
		return (writer == null) ? new String(cb, 0, nextChar) : null;
	}

	/**
	 * Write the contents of this BodyJspWriter into a Writer. Subclasses are
	 * likely to do interesting things with the implementation so some things
	 * are extra efficient.
	 * 
	 * @param out
	 *            The writer into which to place the contents of this body
	 *            evaluation
	 */
	public void writeOut(Writer out) throws IOException {
		if (writer == null) {
			out.write(cb, 0, nextChar);
			// Flush not called as the writer passed could be a BodyContent and
			// it doesn't allow to flush.
		}
	}

	/**
	 * Sets the writer to which all output is written.
	 */
	void setWriter(Writer writer) {
		this.writer = writer;
		closed = false;
		if (writer != null) {
			// According to the spec, the JspWriter returned by
			// JspContext.pushBody(java.io.Writer writer) must behave as
			// though it were unbuffered. This means that its getBufferSize()
			// must always return 0. The implementation of
			// JspWriter.getBufferSize() returns the value of JspWriter's
			// 'bufferSize' field, which is inherited by this class.
			// Therefore, we simply save the current 'bufferSize' (so we can
			// later restore it should this BodyContentImpl ever be reused by
			// a call to PageContext.pushBody()) before setting it to 0.
			if (bufferSize != 0) {
				bufferSizeSave = bufferSize;
				bufferSize = 0;
			}
		} else {
			bufferSize = bufferSizeSave;
			clearBody();
		}
	}

	private void ensureOpen() throws IOException {
		if (closed)
			throw new IOException("Stream closed");
	}

	/**
	 * Reallocates buffer since the spec requires it to be unbounded.
	 */
	private void reAllocBuff(int len) {

		if (bufferSize + len <= cb.length) {
			bufferSize = cb.length;
			return;
		}

		if (len < cb.length) {
			len = cb.length;
		}

		bufferSize = cb.length + len;
		char[] tmp = new char[bufferSize];

		System.arraycopy(cb, 0, tmp, 0, cb.length);
		cb = tmp;
		tmp = null;

	}

}
